PhysicsRankPREVIEWTry a problem

THE PRACTICE STUDIO

Go slowly. Ask why. Make it yours.

PRACTICE · MEMBERSIntermediate · Single correct

PRACTICE / AC phase

A phase label must be compared with the voltage

A sinusoidal load has v(t) = 100√2 cos(ωt) V and i(t) = 2√2 cos(ωt − π/3) A.

What average real power enters the load?

Organize the givens & assumptions
  • Voltage peak = 100√2 V
  • Current peak = 2√2 A
  • Current phase relative to voltage = −π/3

Steady sinusoidal voltage and current at the same frequency; passive sign convention with current entering the positive voltage terminal. Average over a complete cycle.

  1. A400 W400\ \mathrm W
  2. B−100 W-100\ \mathrm W
  3. C100 W100\ \mathrm W
  4. D200 W200\ \mathrm W

Try it on paper first. Free sample problems in every collection include the complete reasoning: find one in this collection →